Engine: * Modified gas grenade and added graphics to it (better get a nose clip!) * Added the ability to tint visual gears * Added the ability to tint explosion effects * Birdy's eggs now cause a small green explosion

foreach(dir "Fonts" "Forts" "Graphics" "Locale" "Maps" "Music" "Sounds" "Themes" "Missions" "Names")
  add_subdirectory(${dir})
endforeach(dir)